Datasheet

PGOOD1
EN1 VBST1
DRVH1
LL1 DRVL1
24 23 22 21 20 19
PGND1
TRIP1
V5IN
V5FILT
TRIP2
PGND2
VO1
VFB1
GND
TONSEL
VFB2
VO2
18
17
16
15
14
13
1
2
3
4
5
6
PGOOD2
EN2
VBST2
DRVH2
LL2
DRVL2
7 8 9 10 11 12
TPS51124
www.ti.com SLVS616B –NOVEMBER 2005–REVISED SEPTEMBER 2010
DEVICE INFORMATION
PIN FUNCTIONS
PIN
I/O DESCRIPTION
NAME NO.
DRVH1 21
Synchronous high-side MOSFET driver outputs. LL node referenced floating drivers. The gate drive
O
voltage is defined by the voltage across VBST to LL node flying capacitor.
DRVH2 10
DRVL1 19
Synchronous low-side MOSFET driver outputs. PGND referenced drivers. The gate drive voltage is
O
defined by V5IN voltage.
DRVL2 12
EN1 23
I Channel 1 and channel 2 enable pins. Connect to 5 V or 3.3 V to turn on SMPS
EN2 8
GND 3 I Signal ground pin
LL1 20
Switch node connections for high-side drivers return. Also serve as input to current comparators and input
I/O
voltage monitor for on-time control circuitry.
LL2 11
PGND1 18
Ground returns for DRVL1 and DRVL2. Also serve as input of current comparators. Connect PGND1,
I/O
PGND2, and GND strongly together near the IC. Output discharge current flows through this pin, also.
PGND2 13
PGOOD1 24 Power Good window comparator open drain output for channel 1 and 2. Pull up with a resistor to 5 V, or
O appropriate signal voltage. Current capability is 5 mA. PGOOD goes high 0.5 ms after VFB comes within
PGOOD2 7
specified limits. Power bad, or the terminal goes low, is within 10 ms.
TONSEL 4 I On-time selection pin. See Table 1.
TRIP1 17 Over-current trip point set input. Connect resistor from this pin to GND to set threshold for synchronous
I low-side R
DS(on)
sense. Voltage across this pin and GND is compared to voltage across PGND and LL at
TRIP2 14
over-current comparator.
VBST1 22 Supply input for synchronous high-side MOSFET driver (Boost Terminal). Connect capacitor from this pin
I to respective LL terminals. An internal PN diode is connected between V5IN to each of these pins. User
VBST2 9
can add external Schottky diode if forward drop is critical to drive the MOSFET.
VFB1 2
I SMPS voltage feedback inputs. Connect with feedback resistor divider.
VFB2 5
VO1 1
Output connections to SMPS. These terminals serve two functions: On-time adjustment and output
I
discharge.
VO2 6
5-V power supply input for the entire control circuit except the MOSFET drivers. Connect RC low-pass
V5FILT 15 I
filter from V5IN to V5FILT.
V5IN 16 I 5-V power supply input for FET gate drivers. Internally connected to VBSTx by PN diodes.
QFN PACKAGE
(TOP VIEW)
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